This invention relates to a welding gun apparatus which is chiefly used as an attachment for an industrial robot.
Welding gun apparatuses are known as shown in FIG. 1, for instance, to include a pair of gun arms c, c provided on a gun bracket b in front of a transformer a. The gun arms c, c are operated to open and close by a pressure applying mechanism d provided between the two gun arms c, c. It has been usual with this arrangement that the gun bracket b is attached to a front surface of the transformer a. The entire apparatus is attached to an industrial robot e through the transformer a with the transformer a being used as a supporting member for the entire apparatus. This type of arrangement, however, is inconvenient in that, it becomes necessary to make a casing for the transformer a large in size and thickness in order to ensure having the necessary mechanical strength. Consequently, the entire apparatus including the transformer a contained in such a case is increased in weight. Accordingly, the robot e is less movable. Furthermore, because of the large-sized casing, a mold material such as resin or the like for filling in the casing is increased in amount, and the cost of manufacturing of the apparatus becomes high.
Additionally, there has also been known a robot, as shown in FIGS. 2 and 3, which has a robot main body e.sub.1 movable upwards and downwards along guide bars e.sub.2, e.sub.2. The main body e.sub.1 is provided with a pair of front and rear robot arms e.sub.3, 3.sub.3. A welding gun apparatus is supported, at a front end of a gun bracket b thereof and at a rear end of a transformer a thereof, on the respective robot arms e.sub.3, e.sub.3. Thus, this type of arrangement has almost the same inconveniences as the foregoing type of arrangement in that, because the transformer a is used as a supporting member for supporting the entire apparatus in its cooperation with the bracket b, it is necessary for the transformer a to be increased in its mechanical strength.